The objective of this project is to investigate the mechanism(s) of tetranitromethane (TNM) pulmonary toxicity and carcinogenicity. This project will include studies of the reactions of TNM with cellular DNA and proteins, pharmacokinetics and metabolism, comparison of nasal and alveolar carcinogenicity, and comparison with related nitro-substituted hydrocarbons. Initial experiments were designed to evaluate the in vitro reaction of TNM with purified nucleosides. TNM was added to 10 milli-M solutions of adenosine, guanosine, thymidine, and cytosine in phosphate buffer (pH 7.0, 37 C) for up to 24 hours. Samples were removed and analyzed by high pressure liquid chromatography (HPLC) for the presence of TNM-nucleosides under these reaction conditions. The only products detected by HPLC were the unmodified nucleosides, TNM and nitroform (a degradation product of TNM). Experiments are planned to investigate whether TNM reacts with purified DNA in vitro. The DNA will be reacted with TNM and analyzed by HPLC for modified nucleotides. Subsequent experiments will evaluate the potential reaction of TNM with proteins. associated with DNA and possibly evaluate DNA strand breaks in cells treated with TNM in vitro.